Reference intensity ratio

The Appendix gives calculated patterns based on the results of X-ray structure determinations for the clinker phases. For each pattern, a Reference Intensity Ratio (H23) is included. This is the integrated intensity of the strongest individual reflection (which may be a component of an overlap) relative to that of the strongest peak of corundum in a 1 1 mixture by... 

Many of these difficulties can be monitored and overcome with the use of standards, either internal or external (Zevin and Kimmel 1995). For the internal standard method, a known quantity of standard material is added to an unknown mixture, and the ratio of the intensity of the standard component is compared to a previously determined calibration curve to determine the mass fraction of the unknown (e.g. one or more of the polymorphic components). In the external standard method, the entire composition of the unknown sample is determined simultaneously by comparing the measured intensities and respective calibration constants of reference intensity ratios (determined beforehand), which must all be with reference to the same reference standard. 

The reference intensity ratio method is based on the experimentally established intensity ratio between the strongest Bragg peaks in the examined phase and in a standard reference material. The most typical reference material is corundum, and the corresponding peak is (113). The reference intensity ratio k) is quoted for a 50 50 (wt. %) mixture of the material with corundum, and it is known as the corundum number . The latter is commonly accepted and listed for many compounds in the ICDD s Powder Diffraction File. Even though this method is simple and relatively quick, careful account and/or experimental minimization of preferred orientation effects are necessary to obtain reliable quantitative results. 

Rearranging Equation (10) allows the definition of the so-called Reference Intensity Ratio (RIR) as the ratio of strongest peak of phase a to the strongest peak of standard. s. Since the generally accepted standard for QPA is corundum, the RIR equates to for the phase (where I is the intensity of the strongest peak of the phase a and is the intensity of the strongest peak of corundum) ... 

HIL 00] HILLIER S., Accurate quantitative analysis of clay and other minerals in sandstones by XRD comparison of a Rietveld and a reference intensity ratio (RIR) method and the importance of sample preparation . Clay minerals, vol. 35, p. 291-302, 2000. 

Quantification of the relative abundance of crystalline phases in a multiphase mixture is an everyday problem in a wide range of applications. Common examples are evaluation of the yield in inorganic synthesis and catalytic processes, characterization of raw mineral materials for industrial processes, quality check of fired ceramic products, and many more. While in most cases the required accuracy level of the analysis is a few percent at best, in particular cases such as in the quantification of phase contaminants in technologically important materials, or of hazardous and toxic phases in environmentally dispersed aerosols, the required level of accuracy must be substantially lower than 1 wt% relative abundance. Accuracy levels of 2-3 wt% are commonly reached if standard procedures of quantitative phase analysis by diffraction data are properly performed. Generally employed analytical methods include the internal or external standard method, the matrix flushing method, and the reference intensity ratio method. Very recently, the availability of analysis techniques of powder diffraction data based on full-profile (Rietveld method), originally developed... 

---